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B. H. JOHNSON.

TELEPHONE TRANSMITTER. No. 341,579. Patented May 11, 1886.

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UNITED STATES PATENT OFEIcE.

H EDVARD H. JOHNSON, OF NEW YORK, N. Y.

TELEPHONE-TRANSMITTER.

SPECIFICATION forming part. of Letters Patent No. 341,579, dated May 11, 1886.

Application filed September 12, 1 81. Serial So. 41,512. Model.) Pa ented in England Juno 7, 1&2, No. 5,360.

New York, have invented a certain new and I useful Improvement in Telephones, of which the following is a specification.

Heretofore in the use of telephones having 1 electrodes or contact-points of platinum or similar metal controlled by the vibrations of a diaphragm difficulty has arisen from the fact that such electrodes soon lose their proper adjustment, and therefore fail to act efficiently. I have found that with electrodes made of the metalloid tellurium this difficulty does not occur, for such electrodes maintain their adjustment during a very long period of use. A telephone employing this material therefore forms a permanently efficient instrument.

My invention then consists, mainly, in the use of tellurium for a telephone-electrode.

In carrying out my invention I may make one electrode of tellurium or of other metal faced with tellurium while the other is a piece of platina-foil, or both electrodes may be made of tellurium or of other metal faced therewith.

In the accompanying drawings, Figure 1 is a section of a telephone-instrument embodying my invention, and Fig. 2 an enlarged section of the electrodes thereof.

The case a may be of any desired form. I) is the diaphragm, which is shown as one of n1etal, and is clamped at its edges to the case,

or otherwise secured. The electrode i of tellurium is secured to the center of the diaphragm, either directly or by a stud or projcction, to which the tellurium is soldered, and

one wire, 0, of the circuit is connected with the metal diaphragm; or if a diaphragm of mica or other insulating material is employed this connection is made directly to the electrode,

as will be well understood.

any well-known or desired character, and at the end of the screw it there is a cross-piece, Z, with a section of rubber tube, 91, and a strip of platina-foil, 0, secured to it. The other wire, 25, of the telephone-circuit is connected with this strip of foil.

The parts are to be adjusted so that the platina or similar foil or strip presses upon the tellurium electrode so as to prevent the electrodes from ever separati ng so far that they cannot readily return to their normal position, so that all the vibrations of the diaphragm are responded to from the normal position of the electrodes.

that I claim is- 1. A telephonic instrument having one or more contacts or electrodes of the metalloid tellurium, substantially as set forth.

2. A telephonic instrument having one or both electrodes of the metalloid tellurium and an adjusting device for said electrodes, substantially as set forth.

Signed by me this 1st day of September, A. D. 188i.

EDWD. H. JOHNSON.

\Vit-nesses:

GEO. T. PINCKNEY, WILLIAM G. MOT'l.

The bridge f and adjusting-screw h are of 

